The Preparation And Research For Energy Storage Properties Of Sn-p Based Composite

With the rapid development of energy-saving and environmentally-friendly economy and society,the demand for energy storage equipment in the field of electric vehicles and electrical energy storage is increasing.The research for new and efficient energy storage equipment is imminent.As a new type of energy storage equipment,rechargeable batteries have the characteristics of light weight,high energy density and long cycle life.Its energy storage performance is closely related to electrode materials.In this thesis,SnCl2·2H2O was used as the tin source,and different phosphorus sources were used to prepare three Sn-P-based materials,namely sodium tin phosphate,Tin hydrogenphosphate and tin phosphide and study the reaction mechanism in detail.Using the prepared three Sn-P based materials as anode materials,the energy storage performance in lithium/sodium ion batteries was studied.(1)Using Na3PO4·12H2O as the phosphorus source,NSPO and its composite materials structure were prepared by co-precipitation and solvothermal methods.For the first time,its reaction mechanism and energy storage performance during charge and discharge were studied.Amorphous NSPO/GO was used as the negative electrode material for lithium batteries.At 0.1 and 1 A/g,the reversible capacities were 860 and 434 mA h/g;After 90 cycles at 0.2 A/g,the reversible capacity stabilized at 718 mA h/g,and the capacity retention rate can reach 94%;as a negative electrode material for sodium batteries,the specific charge capacity at 0.1 and 1 A/g is 272 and 163 mA h/g.(2)Using NaH2PO2 as the phosphorus source,pure phase NSPO was prepared by solvothermal reaction by changing the phosphorus-tin ratio.When the phosphorus-tin ratio is 6 and 8,pure phase NSPO can be obtained.With the increase of the phosphorus-tin ratio,the reducing properties of NaH2PO2 began to appear,the side reactions gradually increased,and the size of the obtained samples also gradually increased.When the phosphorus-tin ratio is 12,the reversible capacity of the obtained NSPO/C/GO composite at 0.1 A/g is 255 mA h/g.Sn can be embedded in the inactive matrix Li3PO4(10-8 S/cm)and Li3-xNaxPO4(10-5 S/cm)with high conductivity formed during the charging and discharging process to accelerate the ion diffusion and buffer its' volume expansion during the charging and discharging process.It was found that tin-based phosphate materials also have excellent electrochemical performance in ion batteries.(3)Using NaH2PO2 as the phosphorus source,SHPO materials under different conditions were prepared by solvothermal reaction.And we systematically studied its electrochemical performance in lithium-ion batteries.By changing the binder in the electrode preparation process,it was found that the electrochemical performance of sodium alginate as the binder is significantly better than PVDF.Sodium alginate is essential to improve its electrochemical performance.Among all the samples,the performance of SHPO-180-2 is the best.The charging specific capacities at 0.1 and 2 A/g are 888 and 355 mA h/g;at 1 A/g,after 210 cycles,the capacity remains at 590 mA h/g.It was found that tin-based phosphate materials also have excellent electrochemical performance in ion batteries.(4)Using red phosphorus as the phosphorus source and SnO2 as the precursor,a new solvothermal method was used to prepare the Sn4P3/C/RGO composite material.When the addition amount of C/GO is 0.2g,Sn4P3/C/RGO have the best electrochemical performance used as the negative electrode material of sodium electricity.The reversible charging specific capacities at current densities of 0.2 and 1 A/g are 217 and 122 mA h/g,respectively.